1. Field of the Invention
The present invention relates to a fuel tank fueling device, and more specifically to a fuel cap for a fuel tank fueling device.
2. Description of the Related Art
In conventional fuel tank fueling devices, the fuel cap is opened when fuel is supplied through a fuel inlet pipe. The fuel cap is sealed by pressing a sealing component against the opening (filling neck) of the fuel inlet pipe to prevent fuel vapor in the fuel tank from escaping into the atmosphere. That is, the fuel cap is provided with the sealing component around the periphery of a cylindrical casing. When the fuel cap is screwed onto the opening of the filling neck, the sealing component provides air-tight sealing force, while subject to torque, against the filling neck.
Conventional fuel caps, however, close off the opening by being rotated when attached to the filling neck, so the sealing component is subject to the torque accompanying friction with the filler neck. It has been found that such torque is not readily applied uniformly across the sealing component as a whole, and complicates efforts to improve the sealing properties.